A node SHOULD NOT originate more than RREQ_RATELIMIT RREQ messages
per second. After broadcasting a RREQ, a node waits for a RREP (or
other control message with current information regarding a route to
the appropriate destination). If a route is not received within
NET_TRAVERSAL_TIME milliseconds, the node MAY try again to discover a
route by broadcasting another RREQ, up to a maximum of RREQ_RETRIES
times at the maximum TTL value. Each new attempt MUST increment and
update the RREQ ID. For each attempt, the TTL field of the IP header
is set according to the mechanism specified in section 6.4, in order
to enable control over how far the RREQ is disseminated for the each
retry.